Gasoline composition



United States Patent 3,334,977 GASOLINE COMPOSITION Alexander H. Popkin, Maplewood, N.J., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Oct. 23, 1963, Ser. No. 318,201 8 Claims. (Cl. 44-56) This is a continuation-in-part of copending application Ser. No. 312,859, filed Oct. 1, 1963.

This invention concerns a gasoline composition and, more particularly, a gasoline containing an anti-icing combination.

The problem of carburetor icing and the engine power losses and engine stalling which result therefrom is not a new one. Operators of automotive, aviation, marine and stationary gasoline engines, particularly those in the colder areas of the United States, have long been familiar with the problem. Tests and surveys have shown that most engines are subject to carburetor icing when the atmospheric temperature drops below about 50 F. and when the relative humidity is in excess of about 75%. Such icing is not confined to any particular type of engine or to any particular type of carburetor. When a gasoline engine is first started, the carburetor is immediately chilledto a temperature considerably below the atmospheric temperature due to the refrigeration effect of the vaporization of the gasoline. This reduced carburetor temperature, often as much as 50 F. below the atmospheric temperature, persists beyond the warmup period of the rest of the engine because of the external position of the carburetor and the poor heat transfer to it. On a humid day, moisture in the air entering the carburetor condenses and freezes on the throttle plate and the carburetor walls ad-' jacent thereto. Such freezing occurs most readily during conditions of light load operation. When the throttle is closed to the idle position, ice which forms on the throttle plate and adjacent carburetor walls restricts the flow of air to the engine. The result is the loss of engine power and frequently the engine stalls. The problem is particularly aggravated in the case of engines equipped with carburetors having venturi diameters on the order of 21 millimeters or less and is also more severe in engines having the venturi tube insulated from the carburetor body. Many gasoline engines are equipped with carburetors having these features.

Another factor which has made the problem of carburetor icing more serious in recent years is the volatility of the gasolines now marketed. Tests have shown that a wholly hydrocarbon fuel having an ASTM 50% distillation point by method D-86 above about 310 F. is not subject to stalling during warmup. Present day fuels are considerably more volatile than this. ASTM specifications now permit a maximum 50% distillation point of 284 and most commercial gasolines have 50% distillation point substantially below this maximum. These highly volatile modern gasolines give rise to carburetor icing and stalling difficulties much more frequently than the older, less volatile fuels.

It is, therefore, an object of this invention to provide additives that prevent the carburetor icing experienced in the use of modern gasoline.

The objects of this invention are obtained by employing isopropyl alcohol in combination with a partially amine neutralized composition of monoand dialkyl esters of phosphoric acid.

A variety of phosphorus compounds are known to the art for their sundry functions in gasoline; for example, in copending application S.N. 209,414, the instant inventor has described and claimed an amine salt of monoand dialkyl esters of phosphoric acid. The amine is reacted in stoichior'netric amounts in order to form a fully neu- 3,334,977 Patented Aug. 8, 1967 "ice tralized salt. This product, an effective multipurpose gasoline additive, is an anti-rust agent, a carburetor detergent and deposit modifier.

However, the additive causes excessive amounts of precipitates to be formed under some circumstances. This occurs when the additive is used in combination'with the anti-icing agent isopropyl alcohol where the gasoline has contacted certain slightly alkaline refinery bottoms. This generally occurs where the concentration of the fully neutralized salt is about 40 pounds/ 1000 barrels and the concentration of isopropyl alcohol is about 2 or 3%. The formation of the precipitates is undesirable for many reasons, one being that the precipitates cause filter plugging which results in engine stalling.

It has now been discovered that the formation of precipitates can be greatly reduced by using a partially neutralized composition of monoand dialkyl esters of straight chains. The preferred amine is n-butylamine.

It is preferred that the alkyl group be unsubstituted; how-' ever, for some purposes it may be desirable to have substituent groups, such as hydroxy or halogen. In the reaction, the amine should be employed in an amount of from 30 to 70', preferably 40 to 60%, the stoichiometric amount necessary to fully neutralize the mixture of monoand dialkyl esters. The most preferred additive composition is made using 50% of the stoichiometric amount.

The monoand diesters have from 12 to 20 carbon atoms in each alkyl group. The alkyl groups may be branched and, in some instances, substituted but preferably are unsubstituted and have straight chains. The pre-- ferred esters contain 13 carbonatoms and are prepared by reacting a C oxo alcohol with P 0 Such esterification reactions are described in copending application S.N. 209,414. The following example illustrates the preferred method of preparing the mixture of monoand dialkyl esters of phosphoric acid.

EXAMPLE 1 A 1000 gallon reactor was charged with 1176 pounds of a C oxo alcohol and 278 pounds of P 0 A temperature of about F. was maintained for about 19 hours; a nitrogen atmosphere was maintained in the reactor. The final product consisted of equimolar amounts of themonoand diester. v

The C oxo alcohol used in the prepaartion of the preferred monoand diesters is prepared by the oxonation and subsequent hydrogenation of C olefin. The hydrogenation reaction should be performed in the presence of a suitable catalyst, -e.g., cobalt on a suitable support.

The mixed esters to be neutralized with an amine should be in a ratio in the range of from 1/ 3 to 3/1 mole ratio of monoester to diester. The preferred mixture contains equimolar quantities of the monoester and diester. The following example illustrates a method of preparing the preferred additive composition of this invention.

EXAMPLE 2 A reactor was charged with 1620 grams of the equimolar mixture of monoand diester prepared in Example 1. Kerosene (755 grams) was added to the mixture, a nitrogen blanket was applied, and about 174 grams (50% stoichiometric amount) of n-butylamine were added over a period of one hour. The reaction mixture was maintained at a temperature of 250 F. for 4 hours.

The reaction temperature of the neutralization reaction may vary within the range of from about 220 F. to 35 F., but is preferably in the range of from about 245 to 255 F. The reactants must be maintained at this temperature for a period of at least one hour, preferably for 3 to 18 hours.

The partially neutralized monoand diester composition described herein is a novel composition. It obviously differs from the fully neutralized salt and has advantages thereover as described above. The composition also differs from additive mixtures prepared by partially neutralizing a monoester and diester individually and thereafter combining the individually neutralized esters. This was evidenced by tests showing the instant composition to be superior to the individually neutralized esters with regard to zinc precipitate formation in the presence of selected refinery bottoms.

This additive composition has good anti-rust properties, gives good carburetor detergency, and has combustion chamber deposite modification benefits. It is effective in gasoline in concenrtations of from 8 p.p.m. (2 pounds/ 1000 barrels) to 320 p.p.m. (80 pounds/1000 barrels). It forms a synergistic anti-icing combination with isopropyl alcohol where the alcohol is employed in concentrations of from 0.3 to 4.0 vol. percent. When used in combination, the preferred concentrations are from 50 p.p.m. to 100 p.p.m. of the partially neutralized ester composition and from 0.5 to 3.0 vol. percent of isopropyl alcohol. A particularly desirable anti-icing composition comprises the instant additive and isopropyl alcohol in combination with hexylene glycol in a concentration of from to 80 pounds/1000 barrels, preferably 12 /2 to 30 pounds/1000 barrels of the additives of this invention, 0.5 to 3.0 vol. percent isopropyl alcohol and preferably 1.0 to 1.5% and 0.02 to 0.35 vol. percent, preferably 0.05 to 0.1 vol. percent hexylene glycol. Another effective combination comprises 5 to 80 pounds/1000 barrels, preferably 12V2 to 30 pounds/1000 barrels of the additive of this invention, and 0.02 to 0.35 vol. percent, preferably 0.1 to 0.25 vol. percent hexylene glycol.

Gasolines as contemplated for use in accordance with the present invention have been defined broadly by the American Society for Testing Materials as complex mixtures composed almost entirely of relatively volatile hydrocarbons which vary widely in their chemical and physical properties. Such gasolines are derived from petroleum by a variety of refining processes including fractional distillation, catalytic cracking, hydroforrning, alkylation, polymerization, solvent extraction and the like. They include aromatics, naphthenes, olefins, parafiins and sometimes diolefins. They may be used as fuels for aviation engines, marine engines and stationary engines. Gasoline normally boils between about 80 F. and about 450 F. when tested by ASTM method D-86. Its vapor pressure by ASTM method D-323 varies from about 6 to about 15 pounds/square inch or higher at 100 F., depending upon the particular season of the year during which it is to be used. The additive materials of the invention are of particular application to gasolines having vapor pressures in the upper part of this range, i.e., between 9 and 15 pounds/square inch. The gasolines in which the additive materials of the invention are used may have octane ratings ranging from about 83 up to about 104 or higher. Such gasolines normally contain at least 2 cc. of tetraethyl lead/ gallon and a halo-hydrocarbon scavenger agent in concentrations of about 1.0 to 2.0 theories.

The gasolines in which the additive materials of the invention are incorporated may also contain other additive materials. Examples of such additive materials include solvent oils consisting of hydrocarbon mixtures having a Saybolt viscosity of F. not above 450 seconds, a 50% distillation point above about 350 F. at 10 millimeters of mercury pressure, and an API gravity between about 18 and 28; corrosion inhibitors, such as Santolene C, which is a phosphorus-containing dimer of linoleic acid; gum inhibitors, such as N,N'-disecondary butyl p-phenylene diamine, 2,4-dimethyl-6-tertiary butyl phenol and 2,6-ditertiary butyl-4-methylphenolg dyes, such as 1,4 diisopropyl aminoanthraquinone and p-dimethyl aminoazobenzene; dye stabilizers, such as ethylene diamine; and similar additive materials commonly used in gasolines. The gasolines of the invention will, however, comprise at least 95% of weight of hydrocarbons.

In summary, the instant additive composition prepared by neutralizing a mixture of monoand dialkyl ester of phosphoric acid with from 30 to 70%, the stoichiometric amount of a C to C primary amine is a multipurpose additive which is superior to the fully neutralized salt in that it forms a synergistic anti-icing combination with isopropyl alcohol and does not induce the formation of excessive precipitates in the presence of the antiicing agent isopropyl alcohol.

The precipitation action is induced by some slightly alkaline water bottoms which commonly come into contact with gasoline. The following example shows the superiority of the instant additive composition as compared with the fully neutralized salt.

EXAMPLE 3 A salt was prepared by fully neutralizing a portion of the additive mixture described in Example 1 with n-butylamine. This salt was compared with the additive of this invention described in Example 2.

Two test blends were prepared for comparison:

Blend 1 Gasoline gallons 5 Fully neutralized salt pounds/ 1,000 barrels 40 Isopropyl alcohol percent 2.3

Blend 2 Gasoline gallons 5 Partially neutralized composition (see Example 2) pounds/1,000 barrels-.. 40 Isopropyl alcohol percent 2.3

Each blend was then stirred with 0.5 vol. percent slightly alkaline refinery bottoms for one-half hour at rpm. in a stainless steel tank fitted with a zinc-1010 steel couple. Each blend was then allowed to age without stirring for 23 /2 hours, and was then pumped at mL/min. through a 12.6 cm. 10,11. AC filter while being stirred at 100 rpm. A pressure drop of 5.4 inches of Hg constitutes essentially complete plugging. The results appear in the following table.

TABLE I AAP (inches Hg) Blend 1 4.4

Blend 2 0.5

Gasoline containing only isopropanol 1.0

It is seen that the additive composition essentially obviates the problem of zinc precipitation occasioned by the use of the fully neutralized salt.

The following example illustrates that the additives of this invention enhance the anti-icing efficacy of isopropyl alcohol.

EXAMPLE 4 Gasoline samples were prepared containing various concentrations of the additive composition described in Example 2 and isopropyl alcohol. These samples were then tested in a 1956 Plymouth engine by startin the engine, operating it for a period of 30 seconds at 1500 revolutions/minute, and then permitting the engine to 31 f I 15 @GOI1d5. This procedure was repeated until smooth operation was obtained, the engine being sold at the beginning of each test series. The number of stalls which occurred in each series of tests was noted and taken as an indication of the carburetor icing characteristics of the fuel being tested. The data were obtained at an atmospheric temperature of 40 F. and at from 88 to 92% relative humidity. The results of this test are shown in Table II.

Carburetor icing numbers as presented in Table II.

were also determined. Carburetor icing number is a means for rating the performance of anti-icing additives. A rating of 100 means there were no stalls whereas a rating of designates a condition of maximum stalling.

1 Average of 6-8 tests. 2 42% ofi at 158 F., 62% ofl at 212 F., 91% off at 302 F.

It is seen from the above data that enhanced anti-icing activity is obtained by employing the additives of this invention in combination with isopropyl alcohol.

What is claimed is: p

1. An improved motor fuel composition comprising gasoline which has contacted alkaline refinery bottoms containing from 0.3 to 4.0 vol. percent of isopropyl alcohol and from 8 to 320 p.p.m. of a composition prepared by neutralizing a mixture of monoand dialkyl esters of phosphoric acid with from 30 to 70% of the stoichiometric amount of a C to C primary n-alkyl amine needed to completely neutralize said esters; the alkyl groups in said esters contain from 12 to 20 carbon atoms.

2. A composition according to claim 1 wherein said isopropyl alcohol is employed within the range of from 0.5 to 3.0% and the partially neutralized mixture of esters is present in an amount of from to 100 p.p.m.

3. A composition according to claim 1 wherein the mole ratio of monoand diesters employed is in the range of from 1/ 3 to 3/ 1 mole ratio of monoester to diester.

4. A composition according to claim 1 wherein said primary amine is n-buty-lamine.

5. A composition according to claim 1 monoand diesters are C oxo esters.

6. A composition according to claim 1 wherein said mixture of monoand dialkyl esters are neutralized with 50% of the stoichiometric amount of the C to C primary amine needed to completely neutralize said esters.

7. A composition according to claim 1 containing from 0.02 to 0.35 vol. percent hexylene glycol.

8. An improved motor fuel composition comprising a gasoline which has contacted alkaline refinery bottoms containing from 0.5 to 3.0 .vol. percent isopropyl alcohol and from 50 to 100 p.p.m. of the composition prepared by neutralizing an equimolar mixture of monoand dialkyl esters of phosphoric acid with from 40 to of the stoichiometric amount of n-butylamine needed to completely neutralize said esters; the alkyl groups in said esters containing from 12 to 20 carbon atoms.

wherein the References Cited UNITED STATES PATENTS 3,007,782 11/1961 Brown et al. 44-56 FOREIGN PATENTS 824,630 12/1959 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Assistant Examiner 

1. AN IMPROVED MOTOR FUEL COMPOSITION COMPRISING GASOLINE WHICH HAS CONTACTED ALKALINE REFINERY BOTTOMS CONTAINING FROM 0.3 TO 4.0 VOL. PERCENT OF ISOPROPYL ALCOHOL AND FROM 8 TO 320 P.P.M. OF A COMPOSITION PREPARED BY NEUTRALIZING A MIXTURE OF MONO- AND DIALKYL ESTERS OF PHOSPHORIC ACID WITH FROM 30 TO 70% OF THE STOICHIOMETRIC AMOUNT OF A C1 TO C5 PRIMARY N-ALKYL AMINE NEEDED TO COMPLETELY NEUTRALIZE SAID ESTERS; THE ALKYL GROUPS IN SAID ESTERS CONTAIN FROM 12 TO 20 CARBON ATOMS. 